Sheet supplying devices that can be incorporated in an image forming apparatus include a sheet supply tray or sheet supply cassette detachably attachable to the image forming apparatus that can accommodate an accumulated stack of recording media. The sheet supply tray is generally pulled out and inserted into a frame of the image forming apparatus through an opening formed in one side of the frame. That is, the sheet supply tray can be detachably attached in one direction only.
However, when an image forming apparatus is installed, some installation areas may have an obstacle or obstacles on the side to which the opening is provided. Therefore, in some recent approaches, a single sheet supply tray is configured to be detachably attachable to an image forming apparatus from two directions (as disclosed, for example, in Japanese Patent Application Publications Nos. 2005-255363 and 9-221236). According to this configuration, even if the sheet supply tray cannot be pulled out and inserted into the image forming apparatus from one direction, sheets or recording media accommodated in the sheet supply tray can be set from another direction.
Generally in such sheet supplying devices, a sheet supplying member such as a sheet supply roller is provided at a downstream position in a sheet conveyance direction and a planar bottom member attached to a bottom wall of the sheet supply tray to cause the sheet supply roller to contact a downstream side of a sheet or a recording medium in the sheet conveyance direction.
For example, as disclosed in Japanese Patent Application Publication No. 2005-255363, when the sheet supply tray is pulled out in a direction perpendicular to the sheet supplying direction, the sheet supply roller remains in the frame of the sheet supplying device. Therefore, the bottom plate of the sheet supply tray stays uplifted, and when the sheet supply tray is being pulled out, sheets or recording media remaining on the sheet supply tray can be caught by the frame. This can obstruct the sheet supply tray to be pulled out from the image forming apparatus or damage the sheets remaining on the sheet supply tray.
Accordingly, as disclosed in Japanese Patent Application Publications Nos. 2005-255363 and 9-221236, if the sheet supply tray can be detached and attached in the sheet conveyance direction and the direction perpendicular to the sheet conveyance direction, the sheet supplying device of the image forming apparatus may need to have a mechanism to push down the planar bottom member so that the planar bottom member does not stay uplifted when the sheet supply tray is pulled out in the perpendicular direction. This can bring an increase in complexity in the entire mechanism of the sheet supplying device, and further increase in cost. Meanwhile, when the sheet supply tray is pulled out in the sheet conveyance direction, the sheet supply tray is pulled out while the sheet supply roller on the frame of the sheet supplying device is pressing a sheet or a recording medium, and therefore the sheet supply tray can be removed successfully without the recording medium caught by the frame.